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Post subject: Any mods to reduce amp noise?
Posted: Wed May 09, 2012 4:25 pm
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Any mods out there possible to reduce the noise that amps (tube and solid state) always generate (hum, hiss etc.)? I'm taking about amp self noise and not noise generated by guitar pickups.


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Post subject: Re: Any mods to reduce amp noise?
Posted: Wed May 09, 2012 9:56 pm
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Lower gain preamp tubes such as a 12AY7 or 5751 in place of a 12AX7.

Replace the 6.3 volt AC heater circuit with a 6.3 volt DC heater circuit.

Replace all carbon comp resistors with carbon film or metal film resistors.

Redress all wires in the amp.

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Post subject: Re: Any mods to reduce amp noise?
Posted: Thu May 10, 2012 3:32 am
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bluesky636 wrote:

Replace the 6.3 volt AC heater circuit with a 6.3 volt DC heater circuit.
Replace all carbon comp resistors with carbon film or metal film resistors.
Redress all wires in the amp.


You know what bluesky636 , I tried this mod few time on amps I build and I hear that a good AC heater wiring is has quiet has good DC and easier to build and less cost too.
Many amp have no heater ground, we should had one.

I my experience metal film resistors is a good advice, like you write ,specially tube's plate resistors .
A good wires dress is a must.

And the most neglect; very short wire or component going at each tube's grid , or shielded wire is also a must. This is lack missing on most amp. Myself , I solder resistor or capacitor directly on tube's socket ( at grid ) with 1/8 inch maximum wire. Longer could act like an antenna.

TC5A ,what is the amp you haven your mind ?


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Post subject: Re: Any mods to reduce amp noise?
Posted: Thu May 10, 2012 4:55 am
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bluesky636 wrote:
Lower gain preamp tubes such as a 12AY7 or 5751 in place of a 12AX7.

Replace the 6.3 volt AC heater circuit with a 6.3 volt DC heater circuit.

Replace all carbon comp resistors with carbon film or metal film resistors.

Redress all wires in the amp.


Thanks for the info.

How much improvement on average could one expect in S/N ratio from these mods? Would the changes also have any effect on amp tone (negative or positive)?


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Post subject: Re: Any mods to reduce amp noise?
Posted: Thu May 10, 2012 5:03 am
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stratele52 wrote:
And the most neglect; very short wire or component going at each tube's grid , or shielded wire is also a must. This is lack missing on most amp. Myself , I solder resistor or capacitor directly on tube's socket ( at grid ) with 1/8 inch maximum wire. Longer could act like an antenna.

TC5A ,what is the amp you haven your mind ?


All the amps I've ever come across are too noisy for my taste. I'm now considering doing some recordings using amps but the noise is always a problem.

Amps I have currently are:

Vox Night Train (head and cab)
Marshall Class 5 Combo
Vox Pathfinder 15R
Vox AC4TV
Fender Frontman 25R
Fender Champ 600 RI

Looking to possibly get a Princeton reverb clone.

Salut de Montreal!


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Post subject: Re: Any mods to reduce amp noise?
Posted: Thu May 10, 2012 5:11 am
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TC5A wrote:
bluesky636 wrote:
Lower gain preamp tubes such as a 12AY7 or 5751 in place of a 12AX7.

Replace the 6.3 volt AC heater circuit with a 6.3 volt DC heater circuit.

Replace all carbon comp resistors with carbon film or metal film resistors.

Redress all wires in the amp.


Thanks for the info.

How much improvement on average could one expect in S/N ratio from these mods? Would the changes also have any effect on amp tone (negative or positive)?



No change in tone except less / no noise


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Post subject: Re: Any mods to reduce amp noise?
Posted: Thu May 10, 2012 5:20 am
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TC5A wrote:
stratele52 wrote:
And the most neglect; very short wire or component going at each tube's grid , or shielded wire is also a must. This is lack missing on most amp. Myself , I solder resistor or capacitor directly on tube's socket ( at grid ) with 1/8 inch maximum wire. Longer could act like an antenna.

TC5A ,what is the amp you haven your mind ?


All the amps I've ever come across are too noisy for my taste. I'm now considering doing some recordings using amps but the noise is always a problem.

Amps I have currently are:

Vox Night Train (head and cab)
Marshall Class 5 Combo
Vox Pathfinder 15R
Vox AC4TV
Fender Frontman 25R
Fender Champ 600 RI

Looking to possibly get a Princeton reverb clone.

Salut de Montreal!


Oui , toi aussi tu es de la région ?

Some of those amp are low cost amp even if they cost lot ( ? ) of money . They are mass production. They could need some mod to be quiet but many ( all ? ) are built with printed circuits and could be difficult to mod unless you are experienced to solder components on printed circuit. And not sure they can be modified .

We have to look inside each amp to see what they need to be quiet and if it possible to mod them at reasonable cost.

Louis


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Post subject: Re: Any mods to reduce amp noise?
Posted: Thu May 10, 2012 5:40 am
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stratele52 wrote:
TC5A wrote:
stratele52 wrote:
And the most neglect; very short wire or component going at each tube's grid , or shielded wire is also a must. This is lack missing on most amp. Myself , I solder resistor or capacitor directly on tube's socket ( at grid ) with 1/8 inch maximum wire. Longer could act like an antenna.

TC5A ,what is the amp you haven your mind ?


All the amps I've ever come across are too noisy for my taste. I'm now considering doing some recordings using amps but the noise is always a problem.

Amps I have currently are:

Vox Night Train (head and cab)
Marshall Class 5 Combo
Vox Pathfinder 15R
Vox AC4TV
Fender Frontman 25R
Fender Champ 600 RI

Looking to possibly get a Princeton reverb clone.

Salut de Montreal!


Oui , toi aussi tu es de la région ?

Some of those amp are low cost amp even if they cost lot ( ? ) of money . They are mass production. They could need some mod to be quiet but many ( all ? ) are built with printed circuits and could be difficult to mod unless you are experienced to solder components on printed circuit. And not sure they can be modified .

We have to look inside each amp to see what they need to be quiet and if it possible to mod them at reasonable cost.

Louis


Salut Louis.

Yes most of those amps are inexpensive, but surprisingly the cheapest one of them (Frontman 25R) is the one that gives me the BEST clean tone! But it's also noisy (and the speaker baffle rattles unless at low volume). Not sure if modding would be worth it on the cheapest amps though. If I could get an upgraded Frontman (or a completely different amp with a very similar clean sound but all top notch built) that would be a good place to start I think.


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Post subject: Re: Any mods to reduce amp noise?
Posted: Thu May 10, 2012 6:53 am
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Indeed, you can be happy with the sound of your frontman. Amplifiers at low prices simply means they have to cut somewhere in the quality. That may be why the noise ?

As has now whether these amps can be modified to improve at a reasonable price, hard to say. We have to look and study each amp.

The Frontman 25R amp sells for $ 129 us, according to the Fender 2010 catalog. At this price you could not ask more for this amp. I doubt that price it's worth investing for the better. I don't know if circuit can be modified to silent the amp. He would return cheaper to buy another one unless you are yourself a good technician, the time and spare costs you nothing and in this case you would not ask questions.


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Post subject: Re: Any mods to reduce amp noise?
Posted: Thu May 10, 2012 7:31 am
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Joined: Fri Jul 30, 2010 5:37 pm
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Location: El Paso, TX
I bought a Fender Blues Jr NOS almost 3 weeks ago and have absolutely no problems with noise etc. I couldn't be happier and kick myself for not buying this amp from the start years ago.

I did a lot of research into tube and solid state amps for bedroom practice and potentially for playing in a band live sometime in the next couple years. I was looking that awesome Fender clean blues tone that can get dirty like SRV. I also wanted versatility...something that accepts pedals well and I found the amp I was looking for- Blues Jr NOS. It may be 15 watts and have a 12 inch speaker, but this amp sounds incredible at low volume (3 out of 12). I liked this way amp better than the smaller VOX 4 watt tube amps and the Lil' Night Train. I also considered the Fender Vibrochamp XD...an awesome amp in its own right which is tube with solid state. But because I was really going for that CLEAN tone more than anything else (effects etc) I had to go with the Blues Jr NOS. I tried Blues Jr III's and they just didn't do it for me (would require mods)...too bright, still nice but it did not slay me.

I've had problems with noise with my crappy Line 6 Spider III and wondered if it was the electrical in my condo etc...I had terrible noise etc. I was really worried that the BJ would have problems too, but nothing at all. Incredible product!

:D


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Post subject: Re: Any mods to reduce amp noise?
Posted: Thu May 10, 2012 1:17 pm
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Joined: Mon Apr 05, 2010 2:37 pm
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Location: Natural Bridge, Virginia
stratele52 wrote:
You know what bluesky636 , I tried this mod few time on amps I build and I hear that a good AC heater wiring is has quiet has good DC and easier to build and less cost too. Many amp have no heater ground, we should had one.


You might find this article interesting. Its about a university group experimenting with a ripple free power supply for the 5F6A Bassman:

http://ampbooks.com/home/classic-circui ... AB-ripple/

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Post subject: Re: Any mods to reduce amp noise?
Posted: Thu May 10, 2012 1:20 pm
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Rock Star
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Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
TC5A wrote:
bluesky636 wrote:
Lower gain preamp tubes such as a 12AY7 or 5751 in place of a 12AX7.

Replace the 6.3 volt AC heater circuit with a 6.3 volt DC heater circuit.

Replace all carbon comp resistors with carbon film or metal film resistors.

Redress all wires in the amp.


Thanks for the info.

How much improvement on average could one expect in S/N ratio from these mods? Would the changes also have any effect on amp tone (negative or positive)?


Don't really have any measurements, just my ears. :lol:

12AY7/5751 do sound different from a 12AX7 so in addition to being quieter, there will be a slight change in tone. Slightly thicker and smoother with the lower gain tubes.

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Post subject: Re: Any mods to reduce amp noise?
Posted: Thu May 10, 2012 1:28 pm
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Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
TC5A wrote:
Yes most of those amps are inexpensive, but surprisingly the cheapest one of them (Frontman 25R) is the one that gives me the BEST clean tone! But it's also noisy (and the speaker baffle rattles unless at low volume). Not sure if modding would be worth it on the cheapest amps though. If I could get an upgraded Frontman (or a completely different amp with a very similar clean sound but all top notch built) that would be a good place to start I think.


I have both a Frontman 25R and Champion 600. I replaced the stock speaker with an Eminence Ragin Cajun. I also added some additional screws to tie the bafle board to the cabinet and made a frame to fit between teh grill cloth and baffle board to prevent vibrations. Very quiet up to about 8 with no vibrations. MyChampion 600 has been heavily modded. My thread is here:

viewtopic.php?f=13&t=63259

The amp is very quiet.

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